The reason why the yellow light of Porsche engine is always on is as follows: 1. Sensor problem: Sensors include water temperature, crankshaft position, air flow, intake air temperature, oxygen sensor, etc. When these sensors are damaged, the contact is poor or the signal is interrupted, the ECU of the automobile can't get the engine data accurately, which will lead to the engine fault light. 2, maintenance problems: poor engine maintenance is the most common cause of engine fault lights. If the owner fails to maintain on schedule, coupled with bad driving habits, it will increase the burden of engine operation, and finally the maintenance fault light will light up. 3. Oil quality: Oil quality includes fuel and engine oil. The fuel for automobile filling is generally marked, and the engine oil is also semi-synthetic and fully synthetic. The owner needs to use the engine oil label recommended by the manufacturer. If the owner doesn't add it as required, it will cause the engine to wear for a long time and the fault light will light up. 4. Poor combustion of mixed gas: engine spark plug failure, ignition coil failure, fuel pump failure, oil circuit blockage, etc. Will cause poor combustion of the mixture. 5. Air intake problem: the engine needs air intake when burning. In this process, the air filter is very important. If the air filter of the car is not clean, it will affect the air intake of the car. If it is not cleaned regularly and blocked for a long time, the engine fault light will light up.